Current telecommunications networks supply a variety of telecommunications services to customers, for example via a Multi-Service Access Node (MSAN). The provided services can comprise for example Plain Old Telephone Services (POTS), Digital Subscriber Lines (DSL) or Integrated Services Digital Network (ISDN) lines. The services are supplied via customer subscriber lines, for example copper cables, connected to a customer Main Distribution Frame (MDF). The Main Distribution Frames play a vital role in an operator network as a result of the investments required to create a geographically distributed access network supporting the delivery of the services to the subscribers. The access network is a significant asset and any change to the architecture drives significant incremental cost. Correspondingly, the costs of implementing new technical solutions in the access network are high and appropriate solutions are often not available on the market.
Traditionally, the number of required reconfigurations per time period was relatively low in the access network. Increased competition, regulatory changes, and the introduction of new services are now driving more reconfigurations. Greater numbers of competitive operators taking advantage of Local Loop Unbundling and the evolution of new broadband xDSL services are increasing the rate at which subscribers either change their service or change from one operator to another. Greater pressure is also placed on access network operators as the location of network devices such as a DSLAM (Digital Subscriber Line Access Multiplexer) is moving from the central office to the MDF as primary connection point, i.e. the location where links from the central office are connected to the links to the individual subscribers. This is due to the requirement to reduce connection lengths so that high bit rate services such as ADSL2+ or VDSL2 can be supported for which the rate drops significantly with increasing connection length between subscriber equipment and DSLAM.
The customer MDF is usually located in a service box near to the customers premises. An MSAN is connected to a provider MDF which is also located in the service box. To supply a particular telecommunications service to a customer the service provider must make connections between the customer MDF and the provider MDF. Such connections are typically made manually by a service engineer who must visit the service box and make the connections. New connections are required to be made each time a new service is provided to a customer or an existing service is changed. The problem is to manage physical connections for the services available to the customers, in particular for a big number of customers, e.g. if new customers or new services are added, or when old customers change the service package or terminate one or more services. All these changes traditionally require a visit of the field engineer at the service box. With regard to the huge number of such service boxes deployed servicing of them and maintaining high responsiveness to customers' requests is both expensive and time consuming.
The cost of making the connections has two main components. The first is the fixed cost of providing the equipment to make the connection. The second is the overhead cost associated with the requirement for the service engineer to visit the service box and make the connection. Service providers aim to minimize both of these costs. The overhead cost can be reduced by waiting until there are several connections to be made at the service box at the same time. This has the drawback that a customer may have to wait for the service to be connected. Typically about 5-10% of customer connections are changed per year, which means that 90-95% of connections remain unchanged. Therefore, waiting to providing new services to customers is often not a feasible option. Alternatively service providers can minimize the overhead cost by including a switching matrix between the customer MDF and the provider MDF which allows automated connections to be made from a remote location.
Switching matrixes used for such automated or remote provisioning comprise cross bar, Bene{hacek over (s)} or Clos networks. Bene{hacek over (s)} networks consist of a plurality of stages of interconnected switching elements which allow connecting ingress and egress ports of the switching matrix over paths which can be changed according to the states of the individual switching elements. Cross bar, Bene{hacek over (s)} and Clos networks can provide non-blocking functionality. Whereas cross bar and Bene{hacek over (s)} network are non-blocking, a Clos network can be either blocking, non-blocking or non-blocking after reconfiguration. One problem associated with the cross bar is the initial cost of deployment which increases the fixed costs because the number of cross bars increases with a square relationship between the number of cross bars and the number of cross paints.
A problem in existing networks is that the number of connections to the MDF is specified by the existing cables and the switching matrix needs an according number of ingress and egress ports. For example, the cable from the provider MDF to the central office of the operator may have 100 lines and the customer MDF may be designed for the connection to 100 lines to the subscribers. In contrast, a Bene{hacek over (s)} network comprising 2×2 switching elements is suitable to connect 2n ingress ports with 2n egress ports where n is an integer. For numbers of ingress and egress ports which deviate from integer powers of 2, the number of switching elements can be reduced without loss of functionality, e.g. the non-blocking properties, in order to save space and costs for the switching matrix. Accordingly, the corresponding network can be called a reduced Bene{hacek over (s)} network. However, the reduced number of ports and switching elements causes an asymmetry in the switching matrix. This leads to increased production costs, in particular if the size of the switching matrix requires a subdivision onto a plurality of different circuit boards.